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Success of hatchery‐reared juvenile white sturgeon ( Acipenser transmontanus ) following release in the Kootenai River, Idaho, USA
Author(s) -
Ireland S. C.,
Beamesderfer R. C. P.,
Paragamian V. L.,
Wakkinen V. D.,
Siple J. T.
Publication year - 2002
Publication title -
journal of applied ichthyology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.392
H-Index - 62
eISSN - 1439-0426
pISSN - 0175-8659
DOI - 10.1046/j.1439-0426.2002.00364.x
Subject(s) - sturgeon , fishery , fish <actinopterygii> , hatchery , geography , tribe , juvenile , archaeology , ecology , biology , sociology , anthropology
In 1990 a conservation program began to evaluate the feasibility of using aquaculture to aid recovery of the white sturgeon population in the Kootenai River. Because of a virtual lack of recruitment during the past two decades, the population was formally listed in 1994 as endangered under the U.S. Endangered Species Act of 1973. Recovery program goals are to preserve the genetic variability of the population, rebuild. natural age class structure, prevent extinction, and restore .natural recruitment. Mature wild fish are captured prior to spawning and bred to produce four to 12 separate families per year of four to 10 adults per family at breeding age: We released 2630 age 1-4 juvenile white sturgeon from 1992 to 1999. Subsequent catches of 39 wild and 620 hatchery juveniles in an annual monitoring program confirm that wild recruitment of Kootenai River white sturgeon is very low. Subsequent recaptures of hatchery fish indicate that significant numbers survived introduction and grew. Release-recapture and catch curve analyses suggest that average annual survival rates for hatchery-reared juveniles may approach 60% for the first year following release and 90% in subsequent years. Growth rates and condition factors within 3 years after release were often poor as many hatchery fish adapted to natural conditions. Growth rates increased after the initial adjustment period. Average growth increments for all recaptured hatchery fish were 6.4 cm year and 0.206 kg year. These rates are slightly less than the median rate reported for other white sturgeon populations. Growth varied substantially among individuals. Some fish grew little even after 3 years but others grew up to 60 cm after 8 years at large. Relative weight decreased between release and recapture for 77% of recaptured hatchery sturgeon. Relative weights were 88% of optimum at release, 78 % of optimum at recapture, and increased with period at large. Relative weight at recapture was inversely correlated with growth in length and opposite to our initial expectations that higher condition would accompany faster growth. No obvious patterns in survival or growth of juveniles could be related to size, time, or condition of release. These initial results provide a basis for adjusting releases of hatchery fish consistent with the conservation goal of the hatchery program and also provide a baseline for comparison with the results of future monitoring to determine carrying capacity of the Kootenai River system for juvenile sturgeon.